Clutch with plural fluid releasing means

ABSTRACT

A clutch pedal is connected by a master cylinder and clutch cylinder through an operating valve with the clutch of a motor car so that the clutch can be disengaged and engaged by an operator before shifting the gear transmission. By operation of electromagnetic control valves, a source of pressure fluid can be connected with the operating valve to operate the same to supply pressure fluid to the clutch cylinder without operation of the clutch pedal. The control valves have another position in which the source of pressure fluid is disconnected while fluid is discharged through the control valves into a low pressure region by a spring-biased piston of the operating valve. The operating piston moves first rapidly, and then slowly while fluid is discharged from the operating cylinder through a throttle, and the clutch performs a corresponding movement first quickly and then slowly to the engaged position as required for shifting to a higher gear. Control means electrically control the electromagnetic control valve for automatic operation of the clutch during up and down shifting of the transmission.

United States Patent [191 Espenshied CLUTCH WITH PLURAL FLUID RELEASINGMEANS [75] Inventor: HelmutEspenshied,Ludwigsburg- Pflugfelden, Germany[73] Assignee: Robert Basch GmbH, Stuttgart,

Germany [22] Filed: Feb. 1, 1972 [21] Appl. No.: 222,485

[30] Foreign Application Priority Data Feb. 3, 1971 Germany P 21 04934.3

[56] References Cited UNITED STATES PATENTS 7/1956 Weaving et a1. 192/83X 12/1966 McRay et al 192/91 R X Primary Examiner-Benjamin W. WycheAttorney-Michael S. Striker [451 Aug. 14, 1973 [57] ABSTRACT A clutchpedal is connected by a master cylinder and clutch cylinder through anoperating valve with the clutch of a motor car so that the clutch can bedisengaged and engaged by an operator before shifting the geartransmission. By operation of electromagnetic control valves, a sourceof pressure fluid can be connected with the operating valve to operatethe same to supply pressure fluid to the clutch cylinder withoutoperation of the clutch pedal. The control valves have another positionin which the source of pressure fluid is disconnected while fluid isdischarged through the control valves into a low pressure region by aspring-biased piston of the operating valve. The operating piston movesfirst rapidly, and then slowly while fluid is discharged from theoperating cylinder through a throttle, and the clutch performs acorresponding movement first quickly and then slowly to the engagedposition as required for shifting to a higher gear. Control meanselectrically control the electromagnetic control valve for automaticoperation of the clutch during up and down shifting of the transmission.

Patented Aug. 14, 1973 2 Sheets-Sheet 1 F ig. 7

Patented Aug. 14, 1973 2 Sheets-Sheet 2 CLUTCH WITH PLURAL FLUIDRELEASING MEANS BACKGROUND OF THE INVENTION The present inventionrelates to control apparatus for actuating the friction clutch of amotor car having a shiftable gear transmission. The clutch pedaloperates a master cylinder and piston device which communicates with aclutch cylinder and piston device operating the clutch.

Clutch control devices of this type have asimple construction, but havethe disadvantage that they have to be operated by the drive of the motorcar for shifting the transmission to a higher or lower stage. Thefrequent operation of the spring-biased clutch pedal is not only tiringfor the driver, but proper operation of the clutch during up and downshifting depends on the skill of the driver.

SUMMARY OF THE INVENTION It is one object of the invention to overcomethe disadvantages of known control apparatus for the clutch of a motorcar, and to provide a clutch control apparatus which controls the clutchoperation in such a manner that smooth gear shifting is obtained.

Another object of the invention is to provide a hydraulic controlapparatus which operates the clutch as required for shifting to a highergear stage or to a lower gear stage.

With these objects in view, an operating valve is connected with themaster cylinder of the clutch pedal and with the clutch cylinder of theclutch, and controls the flow into the clutch cylinder. The operatingvalve can be actuated from the master cylinder, but also by controlvalve means which are automatically operated to connect the operatingvalve either to a low pressure region, or to a source of pressurefluidby which the operating valve is actuated to control the clutch bymeans of the clutch cylinder. In order to achieve a slow return of theclutch to the engaged position, fluid from the operating valve can alsobe automatically discharged through a throttle.

The control apparatus of the invention makes it possible to quicklydisengage the clutch when shifting to a higher gear, and to permit theclutch to engage with a predetermined speed. When the gear transmissionis to be shifted from a high gear stage to a low gear stage, theclutchis quickly reengaged after disengagement and changing of the gearswithout operation of the clutch pedal by the driver. The driver controlsthe clutch operation only during shifting from neutral to the first gearstage, and then preselects upshifting or downshifting of the gear stageswhereupon the clutch is automatically operated at the required speed. Inthis manner, an optimal clutch operation is obtained, which isindependent of the skill of the driver, and the time required forshifting the transmission and disengaging and engaging the clutch isvery short.

The arrangement is such that the automatic operation can be overruled atany time by the driver operating the clutch pedal.

A clutch control apparatus for a motor car in accordance with apreferred embodiment of the invention,

comprises clutch means biased to an engaged position; a clutch cylinderand a clutch piston for moving the clutch means to a disengagedposition; operator controlled biased clutch actuating means, such as thepedal; a master cylinder and a master piston operated by the clutchactuating means; operating valve means including biased operatingpistons, and operating cylin' der means communicating with said mastercylinder and said clutch cylinder so that upon operation of the masterpiston by said clutch actuating means, said clutch piston operates saidclutch means to said disengaged position; a source of pressure fluid,such as a pump; control valve means, preferably including two controlvalves, having a normal position disconnecting the pressure source fromthe operating cylinder means and connecting the latter with a lowpressure region, and a first control position connecting the source ofpressure with the operating cylinder means so that said biased operatingpiston means rapidly presses fluid into said clutch cylinder for rapidlydisengaging the clutch means; and control means for moving the controlvalve means to the first controlled position for disengaging the clutchmeans, and then to the normal position so that low pressure in theoperating cylinder permits the biased operating piston to draw fluidfrom the clutch cylinder so that the clutch means moves rapidly to theengaged position.

In the preferred embodiment, the apparatus comprises a relief throttle,and the control valve means have a second controlled position connectingthe operating cylinder means with the relief throttle so that the clutchmeans moves slowly to the engaged position. The control means includeselectronic means, and switch means operated by the operating pistonmeans and electrically connected with electromagnetic shift ing means ofthe control valve means so that the latter are shifted between thenormal position and first and second control positions.

The apparatus comprises a selector lever which is manually operatedbetween a first selecting position for shifting to a higher gear, asecond neutral position, and a third selecting position for shifting toa lower gear. Selector switches are actuated by the selector lever andconnected with the control means so that the control means move thecontrol valve means from the first controlled position only to thenormal position when the selector lever is in the third position, andsuccessively move said control valve means to the normal and secondcontrolled position when the selector lever is in the first selectingposition.

The novel features which are considered as characteristic for theinvention are set forth in particular in the appended claims. Theinvention itself, however, both as to its construction and its method ofoperation, together with additional objects and advantages thereof, willbe best understood from the following description of specificembodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is partly a schematic view, andpartly a diagram illustrating an embodiment of a control apparatus ofthe invention, partially in section; and

FIG. 2 is an axial sectional view illustrating on an enlarged scale,operating valve means used in the embodiment of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring first to FIG. 1, afriction clutch 2 connects a drive shaft driven by a combustion engine,not shown,

with an output shaft 4 connected with the input shaft of a geartransmission, not shown. A pot-shaped clutch member 5 is secured todrive shaft 3 and have a friction lining 6. The output shaft 4 carries acoupling disk 7 which is operable by a pressure plate 8 which isoperated by a sleeve 9 mounted on output shaft 4 for axial movement, andis biased by a spring 9 toward the pressured plate 8. A double armedlever 10, mounted on a stationary portion of housing 1 for angularmovement, engages a flange of sleeve 9, and is operable by a clutchpiston 11 when fluid is supplied into the clutch cylinder 12 through aconduit 13 leading to an opening in a housing part 31 of an operatingvalve 15. When fluid suchas oil flows into clutch cylinder 12, theclutch 2 is disengaged against the action of spring 9 which tends toengage clutch 2. When fluid is permitted flow out of clutch 12 intooperating valve 15, spring 9 moves clutch 2 to an engaged position.

The cylinder housing portion 31 of operating valve 15 has an opening 16which communicates through a conduit 17 with the master cylinder 18 inwhich a master piston 18' is located, connected by a link with a clutchpedal 19, so that upon depression of the clutch pedal 19, fluid ispressed out of master cylinder 18 and into the opening 16 of theoperating valve housing portion 31.

Housing portion 31 of operating valve 15 has a further opening 20connected by conduit 21 with a schematically illustrated first controlvalve 22 which has two positions I and 11 between which control valve 22is shifted by electromagnetic shifting means 22a under the control ofelectronic control means 28, schematically shown in FIG. 1. A secondcontrol valve has also two positions I and I1, and can be shiftedbetween the two positions by electromagnetic shifting means 25a, alsocontrolled by control means 28.

A switch is spring biased and controlled by an actuator which is engagedby clutch pedal 19 when the same is depressed by the driver. Swtich 30is also electrically connected with control means 28. Furthermore, threeswitches 68, 69, 70 are enveloped by another housing portion 33 ofoperating valve 15, and

nected with the inputs by synchronizing circuits and switching logic sothat synchronized output signals control the functions of thetransmission, not shown, and particularly thee shifting of clutch 2 byclutch piston 11.

Referring again to the control valve means 22, 25, in the illustratednormal position, conduit 21 is connected through control valve 22 andcontrol valve 25 in the positions I with a conduit 76 which leads to aalow pressure region so that fluid from the chamber 60 of the operatingvalve 15 can be quickly discharged.

When control valve 22 is shifted to the first control position 11, asource of pressure fluid, such as a pump 24, is connected by conduit 23and control valve 22 with conduit 21 so that pressure fluid is pressedthrough opening 20 into pressure chamber 60. When control valve 25 isshifted to the second control position 11 thereof, the conduit 21 isconnected with a throttle 27 in a conduit 26 so that pressure fluid frompressure chamber 60 is discharged through conduit 21, control valve 22in position I, and control valve 25 in position [I through throttle 27and conduit 76 to a low pressure region. The low pressure region may berepresented by a container 73a from which pump 24 draws a liquid.

Referring now mainly to FIG. 2, which illustrates the operating valve15, the housing of operating valve 15 includes an upper housing portion31, a central housing portion forming a transverse wall at the lower endof the upper housing portion 31, and a lower housing portion 33 havingan outlet 73 communicating with a conduit 74 which ends in acontainer 75located above operating valve 15, while another conduit opens into alower container 73a.

The upper housing part 31 has a stepped bore including a narrow boreportion 34, and a wider bore portion 35. The upper bore portion 34 isprovided in a tubular narrow neck portion 36 of housing portion 31. Thethree housing portions 31, 32 and 33 have flanges secured to each otherby nut and bolt means 32a.

In the stepped bore 34, 35, a stepped operating piston 37 is slidinglyguided in a fluid tight manner. The

' stepped operating piston 37 has an upper thin piston electricallyconnected with control means 28. Finally,

a selector lever 100, mounted on the steering wheel of the car, controlsthree selector switches 101 which are connected with the control means28. Selector lever 100 has three positions, namely a first selectingposition towhich it is set when automatic shifting to a higher gearstage is desired, a second neutral position, and a third selectingposition when shifting to a lower gear stage is desired. Respectiveselector switches, schematically shown at 101, are actuated in the threeposition of selector lever 100, and influence the electronic means inthe control means 28 accordingly, as indicated by a broken line.

The schematically illustrated control means 28 are not an object of theinvention, and are disclosed inn detail in the copending applicationSer. No. 162,334, filed July 14, 1971, and being assigned to the sameassignee as the present application.

The description of the electronic control means 28 in the copendingapplication is so lengthy, that an inclusion of such a description intothe present application does not seem advisable, particularly since thecontrol means 28 are not an object of the present invention. Briefly,control device 28 has inputs, receiving signals from operator-controlledmeans, and outputs conportion 38 guided in bore portion 34, and a lowerpiston portion 39 guided in bore portion 35. The piston portions 38, 39are clamped together by a nut 40 screwed onto a threaded portion ofpiston portion 38.-

Piston portion 39 has a stepped bore 41 in which a valve body 42 isarranged which has a stem 45 with a washer and nut 46 at the end, and isbiased by a spring 44 to a position seated on an annular shoulder ofbore 41. The end of stem 45 with nut 46 projects slightly beyond the nut40.

When the stepped operating piston 37 is in its uppermost position, asviewed in FIG. 2, it abuts an annular shoulder 47 formed between thebore portions 34 and 35.

The upper piston portion 38 has a blind axial bore 48 ending in a radialbore 48' which opens into a first pressure chamber 49 formed by pistonportion 39 and housing portion 31.

In the lower and wider cylinder bore portion 35, the piston portion 51of a stepped piston 50 is slidably guided. The lower piston portion 52is formed ata shaft or rod 52 guided in a bore 53 in the secondtransverse housing part 32. Piston rod portion 52 has an upper threadedend portion projecting from the upper piston portion 51 and beingsecured by a nut 54 abutting piston portion 51. The nuts 40 and 54 abuteach other in the position of the operating valve shown in FIG. 2.

The transverse housing portion 32 forms a transverse wall which has aboss 55 projecting axially into the wide bore portion 35 of housingportion 31. A spring ring 56 has one end abutting boss 55, and anotherend abutting piston portion 51 of piston 50, and exerting upwardpressure on piston portion 50 so that nut 54 abuts nut 40, while pistonportion 39 abuts the annular shoulder 7 in the upper housing portion 31.

Between the piston portion 39 and the piston portion 51, a secondpressure chamber 60 is formed in housing portion 31 which has theopening connected with conduit 21, as shown in FIG. 1. A third pressurechamber is formed between piston portion 51 and the transverse housingwall 32 and communicates with an opening 14 connected with the clutchcylinder 12 as shown in FIG. 1. In addition to spring 56, a secondspring 59 is located to abut piston portion 51 at the upper end and aflange of the bushing 59 at the lower end, so that bushing 58 is biasedto the illustrated position abutting a flange 57 of piston rod portion52 which is upward biased by spring 56 together with piston portion 51.

The transverse housing wall portion 32 has a conduit passingtherethrough in the form of a stepped bore 62 in which a valve body 63is guided which cooperates with an annular seat 64 formed between thetwo parts of the stepped bore 62. A spring 65 urges a projection 66 ofvalve body 63 against the bottom face of the bushing 58. When due toupward movement of bushing 58, spring 65 can move valve body 64 upward,a passage is established between the third pressure chamber 61 and thecontrol chamber 67 in the lower housing part 33.

Three electric switches 68, 69, 70 are mounted within the controlchamber 67, which is filled with fluid. Switches 68, 69 are locatedspaced from each other in axial direction on one side of the controlchamber 67, and the intermediate switch 70 is located on the other sideof control chamber 67 so that the actuating projections 71 screwed by anut 71a to the piston rod portion 52 operates the actuators of theswitches 68, 69 and 70 when the operating piston 50 is moved. Switch 70is substantially equidistant from switches 68 and 69 in the axialdirection of operating valve 15.

The transverse housing portion 62 has an insulated channel 72 for acable 72 which is connected with control means 28, as schematicallyindicated in FIG. 1, and has three connectors 72a, 72b, 72c respectivelyconnected with switches 68, 69 and 70.

Control chamber 67 has an outlet 73 which is connected by a conduit tothe containers 75 which is located higher than the highest pressurechamber 61, so that pressure c hambers 61, 60 and control chamber 67 arealways filled with the operating fluid. As noted above, the pressurechamber 60 is connected by opening 20 with conduit 21 which leads to thecontrol valve means 22, 25.

OPERATION cated by broken lines, a signal to the control means 28 whichdisconnects the control means 28 from the voltage so that the followingoperations are carried out without interference of the semi-automaticcontrol of control means 28. As the clutch pedal 19 is being depressedby the driver, pressure fluid is displaced from master cylinder 18through conduit 17 to the opening 16 into the ducts 48, 40 in pistonportion 38 and into the first pressure chamber 49 so that the steppedpiston 37 moves downward, and since nuts 40, 54 abut each other, piston50 also moves downward against the action of spring 56 so that thevolume of the second pressure chamber 60 is not varied. A downwardmovement of pistons 50 with piston portions 51 and 52 presses the fluidin the third pressure chamber 61 out of opening 14 and through conduit13 to the clutch cylinder 11 which disengages clutch 2 by operation oflever 10.

Due to the fact that the downward movement of piston portion 51compresses the spring 59, bushing 58 presses against the projection 66of valve body 63 which abuts the annular seat 64 so that no fluid canflow out of the pressure chamber 61 into sure chamber 67 with the low73.

When the clutch 2 is disengaged in this manner by an operation of thedriver, the gear shift lever, not shown, is operated to shift the geartransmission from neutral to the first gear stage, whereupon the driverslowly releases the clutch pedal 19. Spring 56 acts now on pistonportion 51 of the lower piston 50, and through nuts 54, 40 on the pistonportion 39 of the upper stepped piston 37 so that the fluid in the firstpressure chamber 49 is pressed through'opening 16 and conduit 17 intothe master cylinder 18 to urge the clutch pedal 19 to its normalinoperative position. At the same time, pressure fluid in clutchcylinder 12 is urged by clutch piston 11 due to the action of spring 9to flow through conduit 13 and opening 14 into pressure chamber 61 whosevolume increases due to the upward movement of pistion 50 by spring 56.

When clutch pedal 19 moves to its normal inoperative position, itreleases the actuator 29 of the switch 30 so that the electric controlmeans 28 are again operative, and ready for a semi-automatic shiftingoperation.

Assuming that the transmission is to be shifted to the second stage, theselector lever is placed in the selecting position associated withupward shifting of the transmission, the corresponding selector switch101 is operated, and a signal is given to the control means 28.

The electronic control means 28 generates a pulse to the electromagneticshifting means 22a of control valve 22 so that the same is shifted fromthe position I to the position II in which the outlet conduit 23 of thepump 24 is connected with conduit 21, opening 20, and the secondpressure chamber 60'so that the pressure fluid drives the operatingpistons 50, 51, 52 rapidly downward so that pressure fluid is pressedout of pressure chamber 61 through opening 14 and conduit 13 into clutchcylinder 12 so that clutch piston 11 and lever 10 disengage the clutch,without operation of the clutch pedal 19 by the driver. The secondcontrol valve 25 remains in its illustrated normal position.

The transmission of the car, not shown, is designed so that afterdisengagement of clutch 2, and operation of the gear shift, the gears ofthe two stages have to be synchronized. For properly and quicklyshifting the pressure outlet opening the low pres-.

transmission to a higher gear stage, it is desirable that the clutchvery quickly moves towards the engaged position, but is slowed downduring the last part of the movement to obtain a smooth engagement ofthe parts of the friction clutch. The clutch should move as fast aspossible during the first part of the clutch engaging movement so thatthe clutching time is as short as possible. This is accomplished asfollows:

When during downward movement of thee stepped operating piston 50, theprojecting portion 71 of piston rod 52 engages the actuator of theswitch 69, the electronic control means 28 receives a correspondingpulse indicating the position of the stepped operating piston 50. Whenclutch 2 is disengaged, as described above, control valve 22 is shiftedback from position II to the normal position I, and since control valve25 is still in the position I, pressure fluid from pressure chamber 60can be discharged through conduit 21, control valve 22, 2S and conduit76 to the low pressure region of container 76a. The reduction ofpressure in the pressure chamber 60, permits spring 56 to push operatingpiston 50 back into the chamber 60 in a rapid movement. When projectingportion 71 of operating piston 50,51,52 engages the actuator of switch70, a signal is given to the electronic control means 28 through thecable 72 so that the control means 28 generates a pulse to theelectromagnetic shifting means 25a of the second control valve 25whereby control valve 25 is shifted to the control position ll. Thisends the rapid movement of clutch 2 to the engaged position, sincepiston portion 51, pressing the fluid out of chamber 60, has to forcethe fluid through control valve 25 in position II and through thethrottle 27 into the discharge conduit 76, and due to the throttle 27the movement of piston 50 and of the clutch are slowed down so that thetwo clutch parts smoothly engage.

When piston portion 51 with nut 54 again engages nut 40 and is stopped,the actuator of switch 68 is operated and transmits a signal indicatingthe end position of the operating piston 50 to the electronic controlmeans 28 which generates a pulse for shifting control valve 25 back tothe normal position I. Successive gear shift operation toward highergear stages are carried out in the same manner, with selector lever 100remaining in the position for shifting up.

For shifting the gear transmission down in an automatic operation underthe control of control means 28, selector lever 100 is turned to theposition corresponding to downward shifting and the respective actuatedselector switch 101 transmits a signal to the control means 28. When thegas supply is interrupted by the operator, electronic control means 28transmits a signal to the electromagnetic shifting means 22a of controlvalve 22 which is shifted to the control position ll so that pressurefluid from the pump 24 enters the pressure chamber 60, and rapidly movesthe stepped operating piston 50 downward against the action of spring 56so that fluid flows from pressure chamber 61 and through opening 14 andconduit 13 into the clutch cylinder 12 so that clutch 2 is quicklydisengaged. The gear shift lever, not shown, is operated whereupon it isnecessary to engage clutch 2 as quickly as possible. During the downwardmovement of the stepped operating piston 50, 52, switch 69 is closed byprojection 71 but causes the electronic control means 28 to transmit asignal to electromagnetic shifting means 22a whereby the control valve22 is shifted to the normal position l.

Both control valves 22, 25 are now in the respective positions I, sothat the pressure fluid can rapidly flow out of the pressure chamber 60due to the fact that throttle 27 is not effective. In this manner, theclutch is rapidly closed and engaged after a gear shift operation to alower gear stage. Thereupon the gas pedal, not shown, is operated by thedriver, and after obtaining of synchronism between the gears of thetransmission, the transmission is shifted to the next lower gear stage.During the automatic shifting operations, the stepped piston 37 remainsin its upper position, abutting a shoulder 47 of housing 32. However,the automatic clutch operations can be overruled at any time byoperation of clutch pedal 19 by the driver. When clutch pedal 19 isdepressed, actuator 29 of switch 30 is operated so that the electroniccontrol means 28 is disconnected in the same manner as described for thefirst shifting operation from neutral to the first gear stage.

The valve 42 serves the purpose of replacing leakage losses in theconduit 17 and master cylinder 18. This is automatically effected whenthe pressure chamber is supplied with pressure fluid by valve 22 in theposition II. The high pressure in the pressure chamber 60 urges valvebody 42 upwards against the action of spring 44 so that it is lifted offthe annular seat 43 and permits pressure fluid to enter the pressurechamber 49 and conduit 17.

Clutch 2 is subject to a certain wear so that the distance varies whichthe clutch pedal 19 has to move when operated by the driver. The valvebody 63 is provided for compensating the greater distance which theclutch 2 has to move due to wear. The increased volume of clutchcylinder 1 1 is not compensated by an accordingly increased distance ofmovement of the operating pistons 50, but valve body 63 opens so thatfluid is discharged through the conduit 62 into the space 67 and intothe low pressure container 75. This discharge occurs every time when theoperating piston 50 moves to its upper end position in which valve body63 is lifted off its seat 64 by spring 65 due to the higher position ofbushing 58.

Since the control chamber 67 is filled with pressure fluid, the switches68, 69, 70 are protected from condensates and corrosion, and sparking isprevented.-

It is possible to substitute for switch 70, a timing device controllingthe control valve 25. From the above description, it is apparent thatthe clutch 2 can be operated under complete control of the driver bymeans of the clutch pedal 19, and also automatically by control means 28and the control valve means 22, 25.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other types ofclutch control apparatus for a motor car differing from the typesdescribed above.

While the invention has been illustrated and described as embodied in aclutch control apparatus permitting automatic operation of a clutchduring shifting of gears of a motor car, it is not intended to belimited to the details shown, since various modifications and structuralchanges may be made without departing in any way from the spirit of thepresent invention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can by applying current knowledgereadily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this inventionand, therefore, such adaptations should and are intended to becomprehended within the meaning and range of equivalence of thefollowing claims.

What is claimed as new and desired to be protected by Letters Patent isset forth in the appended claims.

I claim:

1. Clutch control apparatus for a motor car, comprising, in combination,clutch means biased to an engaged position; a clutch cylinder and aclutch piston for moving said clutch means to a disengaged position;operator controlled clutch actuating means; a master cylinder and amaster piston operable by said clutch actuating means; operating valvemeans including biased operating piston means, and operating cylindermeans communicating with said master cylinder and said clutch cylinderso that upon operation of said master piston by said clutch actuatingmeans said clutch piston operates said clutch means to move to saiddisengaged position; a source of pressure fluid; control valve meanshaving a normal position disconnecting said source from said operatingcylinder means and connecting the latter with a low pressure region, anda first control position connecting said source with said operatingcylinder means so that said biased operating piston means rapidlypresses fluid into said clutch cylinder for rapidly disengaging saidclutch means; and control means for moving said control valve means tosaid first control position for disengaging said clutch means, and thento said normal position so that low pressure in said operating cylindermeans permits said biased operating pistion to draw fluid from saidclutch cylinder means so that said clutch means moves rapidly to saidengaged position.

2. Control apparatus as claimed in claim 1 comprising relief throttlemeans; wherein said control valve means have a second control positionconnecting said operating cylinder means with said relief throttle meansso that said clutch means moves slowly to said engaged position; whereinsaid control means includes switch means operated by said operatingpiston means; wherein said control valve means include electromagneticshifting means controlled by said switch means to shift said controlvalve means between said positions thereof.

3. Control apparatus as claimed in claim 2 wherein said control valvemeans includes a first control valve and a second control valve havingnormal positions disconnecting said source from said operating cylindermeans and together connecting said operating cylinder means with saidlow pressure region; wherein said first control valve has a workingposition for connecting said source with said operating cylinder means;and wherein said second control valve has a working position forconnecting said operating cylinder means with said relief throttlemeans; and wherein each of said first and second control valves has saidelectromagnetic shifting means.

4. Control apparatus as claimed in claim 1 wherein said operating pistonmeans includes two stepped operating pistons forming in said operatingcylinder means first, second, and third pressure chambers; wherein saidfirst pressure chamber communicates with said master cylinder; whereinsaid second pressure chamber is located between said two operatingpistons and communicates with said control valve means; and wherein saidthird pressure chamber communicates with said clutch cylinder.

5. Control apparatus as claimed in claim 1 wherein said operating valvemeans includes a housing secured to one end of said operating cylindermeans and forming with the same a control chamber into which a pistonrod portion of one of said operating piston means projects; wherein saidcontrol valve means have electromagnetic shifting means; and whereinsaid control means include switch means for controlling saidelectromagnetic shifting means, located in said control chamber andactuated by said piston rod portion.

6. Control apparatus as claimed in claim 1 wherein control means includeelectronic means; and wherein said operator controlled clutch actuatingmeans include a biased clutch pedal, for actuating said master piston sothat fluid flowing through said operating cylinder means operates saidclutch means, and a switch operated by said clutch pedal to disconnectsaid electronic means of said control means so that said control valvemeans are inoperative during operator controlled actuation of saidclutch pedal and clutch means.

7. Control apparatus as claimed in claim 1 wherein said biased operatingpiston means include two operating pistons, and a spring means abuttingsaid operating cylinder means and urging one of said operating pistonsinto abutment with the other operating piston for movement together whenthe pressure in said operating cylinder means is'reduced in said normalposition of said control valve means.

8. Control apparatus as claimed in claim 1 wherein said operating pistonmeans includes two stepped operating pistons forming in said operatingcylinder means first, second, and third pressure chambers; wherein saidfirst pressure chamber communicates with said master cylinder; whereinsaid second pressure chamber is located between said two operatingpistons and communicates with said control valve means; wherein saidthird pressure chamber communicated with said clutch cylinder; andwherein one of said operating pistons which is located between saidfirst and second pressure chambers, includes a biased valve connectingsaid first and second pressure chambers and opening toward said firstpressure chamber.

9. Control apparatus as claimed in claim 1 wherein said operating valvemeans includes a housing secured to one end of said operating cylindermeans and forming with the same a control chamber into which a pistonrod portion of one of said operating pistons projects; wherein saidcontrol valve means have electromagnetic shifting means; wherein saidcontrol means include switch means for controlling said electromagneticshifting means, located in said control chamber and actuated by saidpiston rod portion; wherein said operating piston means includes twostepped operating pistons forming in said operating cylinder meansfirst, second, and third pressure chambers; wherein said first pressurechamber connunicates with said master cylinder; wherein said secondpressure chamber is located between said two operating pistons andcommunicates with said control valve means; wherein said third pressurechamber communicates with said clutch cylinder; and including a biasedvalve in a conduit passing through a transverse wall of said housingseparating said third pressure chamber from said control chamber, saidbiased valve opening said conduit when one of said operating pistonsmoves away from said wall, and clos- 1 1 l2 ing said conduit when saidone operating piston is piston to press fluid from said operatingcylinder means pressed agamst into said master cylinder, and to drawfluid from said 10. control apparatus as claimed in claim 1 wherein saidbiased operating piston means includes an operating piston and a springmeans biasing said operating 5 clutch cylinder into said operatingcylinder means.

1. Clutch control apparatus for a motor car, comprising, in combination,clutch means biased to an engaged position; a clutch cylinder and aclutch piston for moving said clutch means to a disengaged position;operator controlled clutch actuating means; a master cylinder and amaster piston operable by said clutch actuating means; operating valvemeans including biased operating piston means, and operating cylindermeans communicating with said master cylinder and said clutch cylinderso that upon operation of said master piston by said clutch actuatingmeans said clutch piston operates said clutch means to move to saiddisengaged position; a source of pressure fluid; control valve meanshaving a normal position disconnecting said source from said operatingcylinder means and connecting the latter with a low pressure region, anda first control position connecting said source with said operatingcylinder means so that said biased operating piston means rapidlypresses fluid into said clutch cylinder for rapidly disengaging saidclutch means; and control means for moving said control valve means tosaid first control position for disengaging said clutch means, and thento said normal position so that low pressure in said operating cylindermeans permits said biased operating pistion to draw fluid from saidclutch cylinder means so that said clutch means moves rapidly to saidengaged position.
 2. Control apparatus as claimed in claim 1 comprisingrelief throttle means; wherein said control valve means have a secondcontrol position connecting said operating cylinder means with saidrelief throttle means so that said clutch means moves slowly to saidengaged position; wherein said control means includes switch meansoperated by said operating piston means; wherein said control valvemeans include electromagnetic shifting means controlled by said switchmeans to shift said control valve means between said positions thereof.3. Control apparatus as claimed in claim 2 wherein said control valvemeans includes a first control valve and a second control valve havingnormal positions disconnecting said source from said operating cylindermeans and together connecting said operating cylinder means with saidlow pressure region; wherein said first control valve has a workingposition for connecting said source with said operating cylinder means;and wherein said second control valve has a working position forconnecting said operating cylinder means with said relief throttlemeans; and wherein each of said first and second control valves has saidelectromagnetic shifting means.
 4. Control apparatus as Claimed in claim1 wherein said operating piston means includes two stepped operatingpistons forming in said operating cylinder means first, second, andthird pressure chambers; wherein said first pressure chambercommunicates with said master cylinder; wherein said second pressurechamber is located between said two operating pistons and communicateswith said control valve means; and wherein said third pressure chambercommunicates with said clutch cylinder.
 5. Control apparatus as claimedin claim 1 wherein said operating valve means includes a housing securedto one end of said operating cylinder means and forming with the same acontrol chamber into which a piston rod portion of one of said operatingpiston means projects; wherein said control valve means haveelectromagnetic shifting means; and wherein said control means includeswitch means for controlling said electromagnetic shifting means,located in said control chamber and actuated by said piston rod portion.6. Control apparatus as claimed in claim 1 wherein control means includeelectronic means; and wherein said operator controlled clutch actuatingmeans include a biased clutch pedal, for actuating said master piston sothat fluid flowing through said operating cylinder means operates saidclutch means, and a switch operated by said clutch pedal to disconnectsaid electronic means of said control means so that said control valvemeans are inoperative during operator controlled actuation of saidclutch pedal and clutch means.
 7. Control apparatus as claimed in claim1 wherein said biased operating piston means include two operatingpistons, and a spring means abutting said operating cylinder means andurging one of said operating pistons into abutment with the otheroperating piston for movement together when the pressure in saidoperating cylinder means is reduced in said normal position of saidcontrol valve means.
 8. Control apparatus as claimed in claim 1 whereinsaid operating piston means includes two stepped operating pistonsforming in said operating cylinder means first, second, and thirdpressure chambers; wherein said first pressure chamber communicates withsaid master cylinder; wherein said second pressure chamber is locatedbetween said two operating pistons and communicates with said controlvalve means; wherein said third pressure chamber communicated with saidclutch cylinder; and wherein one of said operating pistons which islocated between said first and second pressure chambers, includes abiased valve connecting said first and second pressure chambers andopening toward said first pressure chamber.
 9. Control apparatus asclaimed in claim 1 wherein said operating valve means includes a housingsecured to one end of said operating cylinder means and forming with thesame a control chamber into which a piston rod portion of one of saidoperating pistons projects; wherein said control valve means haveelectromagnetic shifting means; wherein said control means includeswitch means for controlling said electromagnetic shifting means,located in said control chamber and actuated by said piston rod portion;wherein said operating piston means includes two stepped operatingpistons forming in said operating cylinder means first, second, andthird pressure chambers; wherein said first pressure chamberconnunicates with said master cylinder; wherein said second pressurechamber is located between said two operating pistons and communicateswith said control valve means; wherein said third pressure chambercommunicates with said clutch cylinder; and including a biased valve ina conduit passing through a transverse wall of said housing separatingsaid third pressure chamber from said control chamber, said biased valveopening said conduit when one of said operating pistons moves away fromsaid wall, and closing said conduit when said one operating piston ispressed against said wall.
 10. control apparatus as claimed in claim 1wherein said biased operating piston means incluDes an operating pistonand a spring means biasing said operating piston to press fluid fromsaid operating cylinder means into said master cylinder, and to drawfluid from said clutch cylinder into said operating cylinder means.